TOLUTID^. 93 



Mesozoic forms he has been able to examine. These small larval 

 shells are persistent, and often of a different texture to the 

 succeeding whorls of the adult. Professor Dall remarks' that 

 " "When the Volutid^ first begin to appear, and branch off from 

 Fusus, Fasciolaria, and Turhinella, the nucleus or larval shell in 



all these forms was small and shelly "W"e may classify the 



larval shells broadly into two groups — those which were shelly 

 from the beginning ; and those which have succeeded to a horny 

 or uncalcified protoconch, which is lost before the larval shell 



escapes from its ovicapsule There are several forms of the 



shelly nucleus. It undoubtedly preceded the horny one in this 

 group." 



This is followed up by dividing the larval shells into two 

 groups — (1) the Volutoid series, and (2) the Scaphelloid series. 

 Representatives of both these groups occur amongst the Austra- 

 lasian Volutes presently to be described. 



The Volutoid Series. — This series is characterized by the 

 possession of a shelly protoconch, the earliest form of which is 

 called the " trochiform," and is met with in Liopeplum of Upper 

 Cretaceous age, aud in the earlier types of Volutilithes. This 

 kind of protoconch is practically identical with that of the 

 original stock from which those genera sprang. A variation 

 from this, in which the earlier portion becomes flat, is termed 

 " planorboid " ; another, where the turns of the protoconch are 

 more numerous and are considerably elevated, is known as 

 "pupifoi-m"; whilst another important step is taken when the 

 larval shell becomes larger, one-sided, and much inflated, as in 

 the type known as "bulbous." Finally, as a more recent develop- 

 ment in the Volutoid series, there is the enormous protoconch 



in which the "trochiform" type has become greatly exaggerated 

 — known as the " melo " type. 



Turning to the Australasian species here catalogued, the writer 

 recognizes amongst the Volutoid series, representatives of Voluti- 

 lithes, Lijria, Fterospira (a new subgenus), Aulica, Volutoconus, 

 and Amoria. 



The protoconch of the Volutilithes represented, is not of the most 

 archaic type ; it is a modification in which the small trochoid 



1 Trans. "Wagner Free Inst. Sci. Philad. vol. iii. 1890, p. C6. 



